To judge the effectiveness of Western sanctions against Iran, it is important to first establish their purpose. U.S. officials and their European counterparts have set out a number of different goals for the sanctions regime, including deterring the proliferation of nuclear technology across the Middle East, as other countries imitate Iran, and persuading Iran to comply with the UN Security Council’s orders to suspend all nuclear enrichment. The sanctions have met some of those aims and failed to meet others. But for the Obama administration, they have succeeded in one crucial way -- bringing Iran back to the negotiating table. The question, then, is not whether sanctions have worked but whether the strategy they serve is correct.

To begin with, Tehran’s decision to reenter discussions about the future of its nuclear program represents a dramatic about-face. During the January 2011 round of negotiations between Iran and the so-called P5 plus 1 (the five permanent members of the UN Security Council and Germany), for example, Tehran rejected any talk of its nuclear program. For the next 15 months, it refused to meet until the P5 plus 1 accepted the precondition of Iran’s right to enrich uranium. In new talks in Istanbul this past March, however, Iran agreed to discuss its nuclear efforts and dropped its precondition.

The Islamic Republic did not do this out of goodwill but because of tougher sanctions. By demonstrating a willingness to negotiate and working closely with Europe, the Obama administration has rallied many countries behind its efforts. This broad coalition has established increasingly severe sanctions -- results that the United States could not have achieved alone. In March, for example, the European Union banned the largest Iranian banks from the Society for Worldwide Interbank Financial Telecommunication, the main institution used for transferring money between banks across the globe, thereby crippling the ability of Iranian financial institutions to conduct business. And earlier this year, the European Union began imposing